Setsuko Matsumoto

Raflectance Spectra and Band Structures of Quasi-One-Dimensional [Pt(en)2][Pt(en)2X2](ClO4)4 (X=I and Cl, en=ethylenediamine) Crystals

Reflectance spectra of single crystals of [Pt(en) 2 ][Pt(en) 2 I 2 ](ClO 4 ) 4 and [Pt(en) 2 ][Pt(en) 2 Cl 2 ](ClO 4 ) 4 have been measured in the vacuum ultraviolet region up to 25 eV, with synchrotron radiation. Halogen ion-dependent structures observed below 10 eV are ascribed to the transitions related to the valence bands originating from p orbitals of halogens. The one-dimensional band structures for the two compounds are determined from these spectral structures and their polarization-dependences, with the aid of the tight-binding approximation.

Electrochromism and Electronic Structures of Nitrogen Doped Tungsten Oxide Thin Films Prepared by RF Reactive Sputtering

The doping effect of nitrogen on amorphous tungsten trioxide (a-WO3) thin films was investigated with regard to electrochromism and electronic structures. The N-doped thin films exhibit a change in electrochromic coloration from transparent yellow to black, whereas the un-doped thin films exhibit blue coloration. In addition, a new absorption peak related to nitrogen doping is observed at 2.3 eV in photoabsorption spectra during the electrochemical coloration/bleaching process. To explain these experimental results, the electronic structures of N-doped tungsten oxide were calculated by the DV-Xα molecular orbital method.

Intra- ionic transitions of K+ and Rb+ ions in KDP, KDA, RDP and RDA crystals

Abstract Reflection Spectra of KDP(KH 2 PO 4 ), KDA(KH 2 AsO 4 ), RDP(RbH 2 PO 4 ) and RDA(RbH 2 AsO 4 ) were studied in the vacuum ultraviolet region up to 30 eV with use of polarized synchrotron radiation at room and liquid nitrogen temperatures. The e 2 spectra are obtained by the Kram- Kronig analysis. Prominent peaks are observed around 20 eV in KDP and KDA, and around 16eV in RDP and RDA. These multiplet structures are discussed in comparison with the absorption spectra of alkali halides and interpreted as the intra-ionic transition of the K + and Rb + ions.

Preparation and Optical Properties of Zirconium–Titanium–Oxide Thin Films by Reactive Sputtering

Zirconium–titanium–oxide thin films were prepared by multi-target rf reactive sputtering using metallic targets of zirconium and titanium. The compositional ratio of zirconium to titanium in the thin films was precisely controlled through rf power. Zirconium and titanium in the thin films were found to exist as mixtures of chemically bonded ZrO2 and TiO2 from XPS spectra. The zirconium–titanium–oxide thin films with compositional ratio x<0.42 were identified to have a tetragonal crystal structure, whereas those with x≧0.42 were identified to be in the amorphous state. The refractive index of the zirconium–titanium–oxide thin film at a wavelength of 550 nm changed from 2.25 to 2.55 according to compositional ratio x, and the dispersion of the refractive index was analyzed using the Lorentz oscillator model with four oscillators. It was clarified that the estimated oscillator energies E1 (10.5 eV) and E2 (6.5 eV) correspond to zirconium oxide, and that E3 (5.5 eV) and E4 (4.3 eV) correspond to titanium oxide from fundamental absorption spectra and photoconductivity.

Vacuum Ultraviolet Reflectance Spectra of RDP and RDA

Reflectance spectra of RDP and RDA are studied in the VUV region with polarized synchrotron radiation. The optical constants are evaluated by the Kramers-Kronig analysis. The peaks in the low energy region are interpreted on the ground of molecular orbitals of PO43- and AsO43- ions. The peaks above 12 eV are compared with the absorption peaks of alkali halides, providing information on energy levels of Rb+. The temperature dependence of the reflectance spectrum of RDP has shown an abrupt change at the transition temperature.

Optically Controlled Alignment of Liquid Crystal on Polyimide Films Exposed to Undulator Radiation

Liquid crystal (LC) alignment properties on photo-exposed polyimide films were studied in the UV and VUV regions using linearly polarized synchrotron radiation from the Onuki-type polarizing undulator installed in the electron storage ring NIJI-II in ETL. It was found that the LC alignment uniformity depends on the UV and VUV exposure conditions, especially on the wavelength of the radiation. The photoabsorption spectrum of polyimide films was also measured in both UV and VUV regions. It was concluded that at least two mechanisms exist in the photo-induced alignment of LC molecules on the polyimide films.

Study of the Electro-Reflectance of KDP

The electro-reflectance spectra of KDP have been measured by applying an electric field along the z-axis in the photon energy region from 6 eV to 10.5 eV, from which the changes of the real part ( Δ e 1 ) and imaginary part ( Δ e 2 ) of the dielectric constant are deduced. The spectrum of Δ e 2 shows an absorption band-like shape at about 8.3 eV, a little lower energy than the reflection summit, and is interpreted as the change of the absorption intensity relevant to the electron transfer from the oxygen ions of a PO 4 tetrahedron to the nearby hydrogen ions. The spectrum of Δ e 1 shows a dispersion-like shape around the Δ e 2 band, and the change in the region below 7 eV well corresponds to the spectrum of the electro-optic coefficient ρ 63 , though discrepancy is found in the absolute values of Δ e 1 between the one measured and the one estimated from the elctro-optic effect.